The present invention relates to a digital copying machine and an image reader provided with the functions of offline image input and output using a removable storage medium.
Recently, the demand for high speed and multi-functional digital copying machines has arisen, and a digital copying machine provided with a facsimile function, a printer function, etc. in addition to a copy function has been developed. A conventional in digital copying machine will be described below, referring to the figures. FIG. 13 is a block diagram which shows a flow chart for an image signal of a conventional digital copying machine.
As shown in FIG. 13, an image sensor 71 scans an original to convert reflected light from the original to an electric signal. An analog image signal from image sensor 71 is then converted to a digital image signal by an analog-to-digital (A/D) converter 72. The converted digital image signal is subjected to image processing such as edge enhancement, trimming, and halftone processing, and edit processing in an image processor 73. An image signal given by image processor 73 is buffered in a buffer memory 74 for speed control to be given to a laser driver 78. Laser driver 78 drives a semiconductor laser 79 to form an electrostatic latent image by laser beams given by semiconductor laser 79.
The digital copying machine further comprises a central processing unit (CPU) 85, a local area network (LAN) controller 80, a page memory 84, a parallel interface (I/F) 81, a communication control unit (CCU) 82, and a compressor/expander 86 which are mutually connected by a CPU bus 83.
CPU 85 comprises a random access memory (RAM) and a read only memory (ROM) and controls the entire digital copying machine. Page memory 84 has capacity that can store at least one page of image data and is connected to buffer memory 74. Image data stored in page memory 84 is given to laser driver 78 through buffer memory 74 to be printed on paper.
LAN controller 80 communicates with an external equipment through a local area network (LAN). When the digital copying machine is used as a remote printer, an external equipment such as a computer transmits a print control command and image data to the digital copying machine through the LAN. CPU 85 stores the image data received through the LAN into the page memory according to the received print control command.
Using parallel I/F 81, the digital copying machine and an external equipment can be connected one to one. When the digital copying machine is used as a printer for the external equipment, the external equipment transmits a print control command and image data to the digital copying machine through the parallel I/F of the digital copying machine. When the image scanner function of the digital copying machine is used by the external equipment, the external equipment transmits an image read control command to the digital copying machine through parallel I/F 81, and read image data is transmitted to the external equipment from the digital copying machine.
CCU 82 communicates with an external facsimile through a public network using a modem 87. Image data received by the facsimile is expanded in compressor/expander 86, transferred to page memory 84, and printed. Also, image data read for facsimile transmission is stored in page memory 84, compressed in compressor/expander 86, and transmitted to the external facsimile through CCU 82 and modem 87.
Generally, a high-speed digital plain paper copier (PPC) which is capable of copying more than tens of sheets per minute is located in a common space such as a copy room or a hallway. When copying a document which is prepared by a personal computer, etc. in plural copies, a user has to print the original by a nearby printer, take the original to a place where a digital copying machine is located, and then copy the original in plural copies using a sorter, etc. of the digital copying machine. Especially, when a personal computer used by a user is not connected through a LAN, the remote print function of the digital copying machine can not be used, so that copying must be done as mentioned above. In this case, an original image is once printed on paper before copying it, and therefore the image is inevitably degraded.
When a personal computer used by a user is connected to the digital copying machine through a LAN, the user can use the remote print function of the digital copying machine. Therefore, the user can directly utilize a function such as a sorter of the digital copying machine from his personal computer. However, when copying by using the remote print function of the digital copying machine, the user has to go to a distant place where the digital copying machine is located to take printed paper. Also, when copying in large amount using the remote print function, problems such as using up paper and paper jam are likely to occur. To solve these troubles, the user also has to go to the place where the digital copying machine is located. Thus, the utility value of the remote (online) print function in a high-speed digital copying machine is not very high.
When using the image scanner function of the digital copying machine from a user's personal computer online by using the parallel I/F and the LAN, similar problems arise. That is, the user has to go to a distant place where the digital copying machine is located to set an original in the image scanner part of the digital copying machine. Therefore, when the digital copying machine and the user's computer are located a distance apart, it is not useful to use the image scanner function of the digital copying machine online.
Next, a conventional image reader will be described. FIG. 21 is a block diagram showing a flow chart for an image signal of a conventional image reader. An image sensor 171 scans an original to convert reflected light from the original to an electric signal. An analog image signal given by image sensor 171 is converted to a digital image signal by an A/D converter 172, and given to an image processor 173. Image processor 173 performs image processing such as edge enhancement, trimming, halftone processing, pixel density conversion, and gradation level conversion as well as edit processing on the digital image signal. Image data given by image processor 173 is stored in a buffer memory 174.
For controlling the entire image reader, a CPU 185 comprising a RAM and a ROM is provided. CPU 185, image processor 173, buffer memory 174, a DMA (direct memory access) controller 180, and a small computer system interface (SCSI) controller 181 are mutually connected through a CPU bus 183.
DMA controller 180 transfers image data stored in buffer memory 174 to SCSI controller 181 directly. An external equipment such as a computer transmits a control command for the image reader to the image reader through the SCSI controller and receives image data from the image reader. CPU 185 sets the degree of edge enhancement, the gradation level of image data, read density, etc. according to the image read control command.
Such an image reader is connected to an external equipment such as a personal computer one to one using an interface such as a SCSI. Therefore, the image reader is used exclusively by the user of the connected personal computer. When another user uses the image reader, the user has to use the personal computer connected to the image reader or connect the image reader to his personal computer.